1. Field of the Invention
The invention relates to needle bar guiding means for a sewing machine.
2. Description of the Prior Art
Skip stitch sewing machines such as shown and described, for example in U.S. Pat. Nos. 3,793,969, 3,815,529, 3,872,809 and 4,000,706, of The Singer Company include a remotely controllable latch on a latch carrier which is secured to the needle bar of the machine. Such latch carrier is vertically reciprocable by cranking means, and includes means for guiding the reciprocating movements of the carrier to prevent rotation of the needle bar. During the operation of the machine the latch is operable to connect the carrier to and disconnect the carrier from the cranking means. The guiding means has generally included a vertical slot in a guide plate and an element on the latch carrier movable in such slot.
Difficulties with the latching operation have frequently been experienced due to the latch carrier being restrained at times by the guiding means in a position whereat a connection with the cranking means could not be readily effected. A further difficulty has been that of excessive wear on the engaging parts on the guiding means. Such difficulties have been due to excessive friction in the guiding means caused by limitations imposed by the prior art designs on the use of materials for the mutually engaging parts, and have also been due to the failure of the prior art guiding means to positively restrain angular movement of the latching means. The latching difficulties have been further aggravated in many prior art constructions by the required uses of a latch carrier and drive link aligning tang which interferred with the latching operation.